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Showing records 2587 to 2611 of 43611. [First] Page: 1 101 102 103 104 105 106 107 108 109 Last
Oscillatory Rheology of Three-Phase Coal Froths: Effects of Ionic Strength
Na Zhang, Jue Kou, Chunbao Sun, Yangge Zhu
November 30, 2023 (v1)
Subject: Materials
Keywords: coal froths, electrical double layer, froth stability, ionic strength, oscillatory rheology
The rheologic properties of a three-phase coal froth are critical to understanding the interfacial properties that are associated with its stability. Due to the fragile nature of froth, oscillatory rheology was used to make sure that the froths were not damaged during measurement. To reveal the relationship between a coal froth’s rheology and its stability, oscillatory rheology was used in this study. The viscoelastic behaviors of coal froths were analyzed, which illustrated that the storage modulus (G′) of a coal froth is larger than its loss modulus (G″), showing that coal froth is solid-like. The complex viscosity of the coal froths decreased with an increase in angular frequency, meaning that coal froth is shear-thinning. The dependence of froth rheology on ionic strength was investigated, which showed that an increase in ionic strength led to an enhancement of the storage modulus G′, as well as a decrease in tanδ (G″/G′). The coal froths tended to be more rigid and viscous with an... [more]
Adomian Decomposition, Firing Change Process Analysis and Synchronous Control of Fractional-Order Hindmarsh−Rose Neurons in Electromagnetic Field
Tengfei Lei, Haiyan Fu, Hongyan Zang, Lili Huang, Wenqiang Sun
November 30, 2023 (v1)
Keywords: firing, fractional-order HR neurons, ISI bifurcation diagram, synchronous control
In this paper, based on integer-order Hindmarsh−Rose (HR) neurons under an electric field, the fractional-order model is constructed, and the nonlinear term is decomposed by the Adomian decomposition method, and the numerical solution of the system is obtained. The firing behavior of the neuron model is analyzed by using a phase diagram, interspike interval (ISI) bifurcation diagram, sample entropy (SE) complexity, and largest Lyapunov exponent (LLE). Based on the sliding mode control theory, a chaos synchronization controller of the system is designed. Matlab simulation results show that the controller is realizable and effective, and also has the characteristic of fast response, which provides a reference for the control and application of a memristor neural network system.
Effect of High-Voltage Electric Field on Thawing Kinetics and Quality Characteristics of Frozen Beef
Yu Tian, Changjiang Ding
November 30, 2023 (v1)
Subject: Materials
Keywords: beef, FTIR, high-voltage electric field thawing, LF-NMR, SEM, water-holding capacity
This study investigated the impact of high-voltage electric field (HVEF) thawing technology on the thawing rate, water retention characteristics, microstructure, and nutritional composition of thawed beef. Compared with the control group, in which thawing occurred under natural conditions, the experimental group, in which beef was thawed under HVEF (12 kV, 16 kV, 20 kV, 24 kV, 28 kV), showed a significantly shorter thawing time, and the higher the voltage was, the faster the thawing rate. The total loss rate of thawed beef reached its minimum value of (54.2 ± 0.62) % at 28 kV, and the water retention of the experimental group was significantly better than that of the control group (p < 0.05). Therefore, it can be concluded that HVEF thawing enhances the water retention ability of beef. In a color comparison, it was evident that the color of the beef thawed by HVEF was significantly better than that of the control group. The results of scanning electron microscopy (SEM) indicated tha... [more]
Lipid Fractionation and Physicochemical Characterization of Carapa guianensis Seed Oil from Guyana
Stacy O. James, Laziz Bouzidi, R. J. Neil Emery, Suresh S. Narine
November 30, 2023 (v1)
Subject: Materials
Keywords: bioactive compounds, Carapa guianensis, chemical profile, crabwood oil (CWO), dry fractionation, lipids, physical properties, solvent fractionation
The seed oil of Carapa guianensis, known as crabwood oil (CWO), is distinguished for its medicinal and cosmetics applications, attributed to its bioactive components and lipid profile. CWO and its dry and solvent fractionation were studied, with a focus on physicochemical functionality and the partitioning of known bioactive compounds, such as limonoids and sterols. Important bioactive components, including limonoids and sterols, were partitioned depending on the fractionation method; in particular, there is a direct dependence on solvent polarity. There was a very strong solid fraction yield−solvent polarity with a high linear slope of −121.3%. The partitioning of the lipids is significant enough to drive measurable and predictable changes in the physical properties. Palmitic (P: C16:0) and oleic (O: C18:1) fatty acids account for about 60% of the total fatty acid composition of the TAGs of CWO and its fractions. The most abundant limonoid is methyl angolensate (from 28 to 39%), follo... [more]
Review on Waste-to-Energy Approaches toward a Circular Economy in Developed and Developing Countries
Shahabaldin Rezania, Bahareh Oryani, Vahid Reza Nasrollahi, Negisa Darajeh, Majid Lotfi Ghahroud, Kamyar Mehranzamir
November 30, 2023 (v1)
Subject: Environment
Keywords: circular economy, developed and developing countries, policies and regulations, solid waste management, waste-to-energy
International interest in using waste-to-energy (WtE) technology toward a circular economy (CE) is developing, spurred by environmental challenges such as inefficient solid waste dumping, pollution, and resource depletion. Incineration, pyrolysis, gasification, landfill, and anaerobic digestion are standard WtE technologies. Although these methods have been used for many decades, all countries try to implement the best plans based on their technologies and capacities. Therefore, an up-to-date comprehensive study is needed to evaluate the existing barriers to draw a logical roadmap for WtE to CE. Therefore, this review addresses the recent policies adopted by developed and developing countries for WtE technologies. Based on the findings, most countries seek the most cost-effective and environmentally sustainable pathways in WtE to CE; meanwhile, international collaboration and governmental support are needed to overcome the existing barriers and find a sustainable and economically viabl... [more]
Research on Metallurgical Saw Blade Surface Defect Detection Algorithm Based on SC-YOLOv5
Lili Meng, Xi Cui, Ran Liu, Zhi Zheng, Hongli Shao, Jinxiang Liu, Yao Peng, Lei Zheng
November 30, 2023 (v1)
Keywords: deep learning, defect detecting, lightweight, metallurgical saw blade, YOLOv5
Under the background of intelligent manufacturing, in order to solve the complex problems of manual detection of metallurgical saw blade defects in enterprises, such as real-time detection, false detection, and the detection model being too large to deploy, a study on a metallurgical saw blade surface defect detection algorithm based on SC-YOLOv5 is proposed. Firstly, the SC network is built by integrating coordinate attention (CA) into the Shufflenet-V2 network, and the backbone network of YOLOv5 is replaced by the SC network to improve detection accuracy. Then, the SIOU loss function is used in the YOLOv5 prediction layer to solve the angle problem between the prediction frame and the real frame. Finally, in order to ensure both accuracy and speed, lightweight convolution (GSConv) is used to replace the ordinary convolution module. The experimental results show that the mAP@0.5 of the improved YOLOv5 model is 88.5%, and the parameter is 31.1M. Compared with the original YOLOv5 model,... [more]
Screening of Microbial Strains Used to Ferment Dendrobium officinale to Produce Polysaccharides, and Investigation of These Polysaccharides’ Skin Care Effects
Xin Tang, Bulei Wang, Bingyong Mao, Jianxin Zhao, Guangrong Liu, Kaiye Yang, Shumao Cui
November 30, 2023 (v1)
Subject: Biosystems
Keywords: Dendrobium officinale, Fermentation, Limosilactobacillus reuteri CCFM8631, polysaccharides
The microbial fermentation of plants is a promising approach for enhancing the yield of polysaccharides with increased activity. In this study, ten microbial strains, Lactiplantibacillus plantarum CCFM8661, Limosilactobacillus reuteri CCFM8631, Lactobacillus helveticus M10, Lacticaseibacillus rhamnosus CCFM237, Lactilactobacillus sakei GD17-9, Lacticaseibacillus casei CCFM1073, Bacillus subtilis CCFM1162, Bacteroides cellulosilyticus FTJSI-E-2, Bacteroides stercoris FNMHLBEIK-4, and Saccharomyces cerevisiae HN7-A5, were used to ferment Dendrobium officinale. The skin care activity of the resulting polysaccharides (F-DOP) was evaluated in cultured HaCaT and RAW 264.7 cells, and a mouse model. The results indicated that D. officinale medium promoted strain proliferation, and fermentation significantly enhanced polysaccharide yield (up to 1.42 g/L) compared to that without fermentation (0.76 g/L). Moreover, F-DOPs, especially after CCFM8631 fermentation, exhibited an excellent ability to... [more]
Rock-Breaking Characteristics of High-Pressure, Dual-Stranded Water Jets
Yue Pan, Shengyu Zhai, Kangchao Pei, Hao Yuan, Fulin Huo
November 30, 2023 (v1)
Keywords: high-pressure double water jet, jet flow angle, optimal parameters, specific energy for rock breaking
Because of the unclear understanding of the characteristics associated with coupled rock breaking using multiple water jets, a numerical model combining smoothed particle hydrodynamics (SPH) and the finite element method (FEM) was established to investigate the rock-breaking capacity of a high-pressure, double-stranded water jet structure. The effectiveness of this model was verified through field experiments. The study further examined the specific energy required for rock breaking using the high-pressure double water jets and analyzed the effects of jet pressure, nozzle diameter, jet impact angle, and impact point spacing on rock-breaking volume. The results demonstrate that the rock-breaking ability of a high-pressure double water jets is better than that of a single water jet. When the impact angle of the high-pressure double water jets was 15° and the distance between impact points was 2.0 d, the rock damage effect was the best. By comparing the specific energies for rock breaking... [more]
Application of Edible Insect Flour as a Novel Ingredient in Fortified Snack Pellets: Processing Aspects and Physical Characteristics
Agnieszka Wójtowicz, Maciej Combrzyński, Beata Biernacka, Tomasz Oniszczuk, Marcin Mitrus, Renata Różyło, Marek Gancarz, Anna Oniszczuk
November 30, 2023 (v1)
Subject: Materials
Keywords: edible insect flour, extrusion cooking, physical properties, snack pellets
The aim of the study was to develop a suitable recipe for wheat-corn snack pellets fortified with insect flour addition and to evaluate the relevant processing aspects and physical characteristics of the developed products. Varying levels of edible insect flour (10, 20, and 30%) were incorporated into a new type of fortified snack pellet as a half product for further expansion. The effects of the edible insect flour level, as well as processing variables (moisture levels 32, 34, 36% and screw speeds 60, 80, 100 rpm), were analyzed on the extrusion stability and on selected snack pellets’ physical properties processed via single-screw extrusion cooking. This research indicated that an increasing amount of edible insect flour significantly affected the processing output and energy consumption. The incorporation of insect flour in blends significantly increased the specific mechanical energy and efficiency of pellet extrusion, especially at a high moisture level and high screw speed durin... [more]
Atomization of Borosilicate Glass Melts for the Fabrication of Hollow Glass Microspheres
Tobias Helling, Florian Reischl, Andreas Rosin, Thorsten Gerdes, Walter Krenkel
November 30, 2023 (v1)
Keywords: CFD simulation, free-fall atomizer, glass melt atomization, hollow glass microspheres, low melting glass
Direct atomization of a free-flowing glass melt was carried out using a high-speed flame with the aim of producing tiny, self-expanding glass melt droplets to form hollow glass microspheres. Atomization experiments were carried out using a specially adapted free-fall atomizer in combination with a high-power gas burner to achieve sufficient temperatures to atomize the melt droplets and to directly expand them into hollow glass spheres. In addition, numerical simulations were carried out to investigate non-measurable parameters such as hot gas velocities and temperatures in the flame region by the finite volume-based software Star CCM+® (v. 2022.1.1), using the Reynolds-Averaged Navier−Stokes (RANS) turbulence and the segregated flow model. To calculate the combustion process, the laminar flamelet method was used. The experiments and simulations indicated that a maximum gas velocity of about 170 m/s was achieved at the point of atomization in the flame. The particle size distribution of... [more]
Application of Alcohol-Salt Aqueous Biphasic System for the Recovery of Ectoine
Yin Hui Chow, Chin Tee Poh, Phei Er Kee, Hui Suan Ng, John (Chi-Wei) Lan, Li Wan Yoon
November 30, 2023 (v1)
Subject: Biosystems
Keywords: alcohol, aqueous biphasic system, ectoine, recovery, salt
Ectoine is an osmoregulatory compound synthesized by halophiles which has attracted attention in the biotechnology, pharmaceuticals, and cosmetics industries due to its stabilizing and protective properties. Conventional methods for ectoine recovery are complex, costly, and often result in low yields. Therefore, there is a growing interest in exploring simple and cost-effective strategies for ectoine recovery. The aqueous biphasic system (ABS) has been employed for the recovery and purification of numerous biocompounds, but the study of low-molecular weight compounds partitioning in ABS remains limited. This study aimed to investigate the feasibility of alcohol−salt ABS for ectoine recovery from Halomonas salina DSM5928T cells. The influences of types and compositions of phase-forming components, crude load concentration, pH, and adjuvants on ectoine recovery were evaluated. Results revealed that ectoine favoured partitioning into the salt-rich bottom phase of alcohol−salt ABS owing to... [more]
All-Factor Average Method of Reserve Parameters with Crude Oil Volume and Mass Constraints
Doujuan Zhang, Haimin Guo, Yuyan Wu, Cunyuan Chen, Ao Li, Jinyan Zhang, Yonggang Wang
November 30, 2023 (v1)
Keywords: all-factor average method, carry error, crude oil mass constraint, crude oil volume constraint, full permutation combination selection method, reserve parameters
In order to make the average value of each reserve parameter of a set of oil reserves more representative, this paper puts forward the all-factor average method of reserve parameters with crude oil volume and mass constraints. In the first step, the two constraint methods of crude oil volume and mass are adopted to calculate the average value of various parameters of the total items. The weight coefficient when the parameter is averaged is, respectively, the partial derivative of the volume or mass reserve calculation formula with respect to the parameter. Compared with the original calculation results, the average of their parameters all show a shift towards values with a significant share of reserves, especially effective porosity, oil saturation, and crude oil volume factor. The all-factor average method considers a more comprehensive set of factors than the original method. Therefore, each new average parameter should also be much more representative. Since the current reserve spec... [more]
Anti-Inflammatory and Antinociceptive Activity of Herbal Lipospheres of Pentaclethra macrophylla (Fabaceae) Stem Bark Extract
Petra Obioma Nnamani, Edith Obioma Diovu, Ikechukwu Emmanuel Peter, Akachukwu Marytheresa Onwuka, Chiamaka Victory Ogbuanwu, Obiora Emmanuel Abonyi, Brigitta Loretz, Claus-Michael Lehr
November 30, 2023 (v1)
Subject: Materials
Keywords: anti-inflammatory activity, antinociception, herbal liposphere, Pentaclethramacrophylla, solidified reverse micellar solutions (SRMS), stem bark extract
Purpose: Inflammation of various degrees is common among humans. There are associated side effects with orthodox delivery systems and anti-inflammatory agents; hence, the study investigated the characteristics of herbal lipospheres and the anti-inflammatory potency of the lipospheres formulated from Pentaclethra macrophylla with the view to having a drug with a better delivery system and lesser side effects. Methods: Herbal lipospheres were formulated using solidified reverse micellar solutions (SRMS) of P90H and goat fat and characterized for particle size and morphology, pH time dependent analysis, encapsulation efficiency (EE%), and Fourier Transform infrared spectroscopy. The in vitro antinociceptive and anti-inflammatory studies were carried out using membrane stabilization by hypotonicity-induced hemolysis and the determination of anti-platelet aggregatory activity models. The in vivo antinociceptive and anti-inflammatory studies on egg albumin- and formaldehyde-induced arthritis... [more]
Investigating the Mechanism of Continuous−Discrete Coupled Destabilization of Roadway-Surrounding Rocks in Weakly Cemented Strata under Varying Levels of Moisture Content
Lihui Sun, Zhixin Jiang, Yaxin Long, Qingfeng He, Haiyang Zhang
November 30, 2023 (v1)
Keywords: anchorage failure mechanism, continuous–discrete, destabilization mechanism, moisture content, weakly cemented rock
This study examines frequent disasters, including large-scale deformation and collapse, caused by underground mining in weakly cemented strata in Western China. The weakly cemented rock’s unique characteristics, including low strength and easy disintegration, demonstrate a different damage pattern than that traditionally seen in the central and eastern regions. Using Fast Lagrangian Analysis of Continua-Particle Flow Code (FLAC2D-PFC2D) coupling, we model the strata, focusing on the 3-1 coal seam roadway at Hongqinghe mine. This study investigates the damage−rupture−destabilization progression in the peripheral rock under varying levels of moisture content. Our findings indicate that a water content of ω = 5.5% is the threshold for roadway damage, and moisture content 5.5% abruptly increases cracks and shifts the rock’s force chain, causing significant deformation and affecting the ceiling the most. Moreover, higher levels of moisture content weaken the anchor solid’s performance, with... [more]
Discrete-Element-Method-Based Determination of Particle-Level Inputs for the Continuum Theory of Flows with Moderately Cohesive Particles
Kevin M. Kellogg, Peiyuan Liu, Christine M. Hrenya
November 30, 2023 (v1)
Keywords: cohesion, continuum theory, discrete element method, particle flows
In this work, the cohesion-specific inputs for a recent continuum theory for cohesive particles are estimated for moderately cohesive particles that form larger agglomerates via discrete element method (DEM) simulations of an oscillating shear flow. In prior work, these inputs (critical velocities of agglomeration and breakage and collision cylinder diameters) were determined for lightly cohesive particles via the DEM of simple shear flow—i.e., a system dominated by singlets and doublets. Here, the DEM is again used to extract the continuum theory inputs, as experimental measurements are infeasible (i.e., collisions between particles of a diameter of <100 μm). However, simulations of simple shear flow are no longer feasible since the rate of agglomeration grows uncontrollably at higher cohesion levels. Instead, oscillating shear flow DEM simulations are used here to circumvent this issue, allowing for the continuum theory inputs of larger agglomerate sizes to be determined efficient... [more]
Numerical Analysis of Viscous Polymer Resin Mixing Processes in High-Speed Blade-Free Planetary Blender Using Smoothed Particle Hydrodynamics
Kwon Joong Son
November 30, 2023 (v1)
Keywords: mixing processes, mixing simulation, planetary mixer, smoothed particle hydrodynamics, viscous fluid blending
High-speed planetary mixers can rapidly and efficiently combine rheological liquids, such as polymer resins and paste materials, because of the large centrifugal forces generated by the planetary motion of the mixing vessel. Only a few attempts have been made to computationally model and analyze the intricate mixing patterns of highly viscous substances. This paper presents meshless flow simulations of the planetary mixing of polymeric fluids. This research utilized the smoothed particle hydrodynamics (SPH) approach for numerical calculations. This method has advantages over the finite-volume method, which is a grid-based computational technique, when it comes to modeling interfacial and free surface flow problems. Newtonian rheology and interfacial surface force models were used to calculate the dissipative forces in the partial differential momentum equation of fluid motion. Simulations of the flow of an uncured polyurethane resin were carried out while it was mixed in a planetary mi... [more]
Structural Design and Preparation Process Research of Stacked MEMS Gas Sensors for Volatile Organic Compound Gases
Guizhou Wu, Junfeng Wu, Juan Dong, Xinyu Zhang
November 30, 2023 (v1)
Keywords: gas sensitivity characteristics, MEMS gas sensor, porphyrin zinc, volatile organic compounds
To design gas sensors with fast response speed and high sensitivity for the detection of volatile organic compounds, a stacked MEMS sensor was designed in this study. It utilizes porphyrin-sensitive materials and carbon nanotubes to form composite materials, improve the thermal stability of sensitive materials, and conduct sensor gas sensitivity testing. The results show that the design of the thermal insulation structure makes the sensor obtain lower power consumption and more uniform temperature distribution, and the maximum deformation variable is 3.7 × 10−2 μM. Doping carbon nanotubes in porphyrin-sensitive materials can effectively improve their thermal stability, and the sensor is in a safe state at temperatures below 358 °C. The sensor with higher response recovery characteristics at a low concentration of 80 ppm aniline has better response recovery characteristics, with a response time of 33 s and a recovery time of 23 s, respectively; its response recovery characteristics to 1... [more]
Numerical Simulation and Experiment on Pill Coating of Red Clover Seeds under the Action of Vibrating Force Field
Mengjun Guo, Xuyang Cai, Xuejie Ma, Zhanfeng Hou, Xin Tong, Haiyang Liu
November 30, 2023 (v1)
Keywords: EDEM, red clover seeds, rotational speed, seed coating, vibration
In order to solve the problem of the low qualification rate of the pilling and coating of small-grain forage seeds, a vibration force field is introduced to the traditional vertical disk coating machine to promote the mixing of materials and improve the qualification rate of the pilling. Using the typical small-grain forage seed red clover as an example, we used the vibration force field after adding seed powder particles to a coating pot for the theoretical analysis of the force situation, using the discrete element software EDEM to construct a red clover seed simulation model with the coefficient of discretization as the evaluation index. We studied the effects of the rotational speed of the coating pot, the vibration frequency of the pot, the amplitude of the vibration of the pot, and the other operating parameters of the pot on the uniformity of the seed powder mixing, with the pelletization of the pass rate as the physical evaluation standard, using a one-way test to study the eff... [more]
Decentralized Control Strategy for Participation of Electric Vehicles in Distribution Voltage Control
Xin Fang, Juan Li, Yubo Yuan, Xiaodong Yuan
November 30, 2023 (v1)
Keywords: decentralized voltage control, electric vehicle, electric vehicle charging station, rolling optimization
With the accelerating transportation electrification, increasing numbers of electric vehicles (EVs) are connected to distribution networks via electric vehicle charging stations (EVCSs). Due to the uncertain charging behaviors of EV users, concentrated high-power EV charging during peak hours can result in significant undervoltage issues, affecting the regular operation of distribution networks and having detrimental effects on regular EV charging. Conventional EV charging scheduling methods are conducted in a centralized way, requiring extensive investment in communication infrastructure and intensive computing power. Accordingly, this paper proposes a novel decentralized voltage control scheme with the participation of EVs and EVCSs. The proposed control scheme first divides the distribution network into clusters based on a modified modularity index. Then, it applies the rolling optimization-based control of the EVs and EVCSs within each cluster to solve the regional voltage problems... [more]
An Amended Crow Search Algorithm for Hybrid Active Power Filter Design
Shoyab Ali, Annapurna Bhargava, Akash Saxena, Abdulaziz S. Almazyad, Karam M. Sallam, Ali Wagdy Mohamed
November 30, 2023 (v1)
Subject: Optimization
Keywords: crow search algorithm, design, filter, numerical optimization, power quality, swarm intelligence
Hybrid Active Power Filter (HAPF) imbibes the advantages of both passive and active power filters. These filters are considered one of the important technologies for mitigating harmonic pollution in electrical systems. Accurate estimation of filter parameters is a key component to reduce harmonic pollution effectively. In recent years, several optimization approaches have been reported to solve this estimation problem; still, this area is worthy of further investigation. This paper is a proposal for an estimator that can estimate the parameter of HAPF configuration accurately. For evolving this estimator, first, an objective function that mathematically embeds filter parameters and harmonic pollution is presented. For handling the optimization process, an Amended Crow Search Algorithm (ACSA) is proposed. ACSA employs a local search algorithm (in the form of a pattern search) for obtaining optimal results. The analysis of the estimation process is carried out on two HAPF configurations.... [more]
A Novel Hybrid Optimization Approach for Fault Detection in Photovoltaic Arrays and Inverters Using AI and Statistical Learning Techniques: A Focus on Sustainable Environment
Ahmad Abubakar, Mahmud M. Jibril, Carlos F. M. Almeida, Matheus Gemignani, Mukhtar N. Yahya, Sani I. Abba
November 30, 2023 (v1)
Keywords: Artificial Intelligence, boosted tree algorithms, Elman neural network, Fault Detection, Gaussian processes regression, multi-layer perceptron, sustainable development
Fault detection in PV arrays and inverters is critical for ensuring maximum efficiency and performance. Artificial intelligence (AI) learning can be used to quickly identify issues, resulting in a sustainable environment with reduced downtime and maintenance costs. As the use of solar energy systems continues to grow, the need for reliable and efficient fault detection and diagnosis techniques becomes more critical. This paper presents a novel approach for fault detection in photovoltaic (PV) arrays and inverters, combining AI techniques. It integrates Elman neural network (ENN), boosted tree algorithms (BTA), multi-layer perceptron (MLP), and Gaussian processes regression (GPR) for enhanced accuracy and reliability in fault diagnosis. It leverages its strengths for the accuracy and reliability of fault diagnosis. Feature engineering-based sensitivity analysis was utilized for feature extraction. The fault detection and diagnosis were assessed using several statistical criteria includi... [more]
Finite Element Modelling and Experimental Validation of the Graphite Cutting Process
Dayong Yang, Furui Wei, Wei Wang, Yuchen Zhang, Lingxin Zeng
November 30, 2023 (v1)
Subject: Materials
Keywords: chip morphology, crack initiation and growth, finite element modelling, graphite, machined surface morphology
Graphite is extensively used in the engineering field due to its unique properties, and the study of its cutting mechanism has become particularly important. However, the brittle fracture mechanism of graphite makes it rather easy for cracks with a unique pattern of initiation and growth to develop when processing. Herein, the ABAQUS was selected to establish a finite element model (FEM) of the graphite cutting process. The internal crystal structure of graphite was modelled by a Voronoi structure, and a cohesion unit was globally embedded into the solid unit to simulate crack initiation and growth. In addition, the complete process of chip formation and removal was demonstrated. The analysis of the simulation results showed that the graphite material underwent three periodic cycles of material removal during the cutting process, i.e., large, tiny, and small removal stages. Meanwhile, the simulation results indicated that when ac was large enough, the crack gradually grew inside the gr... [more]
Numeric Investigation on the Stability of a Preformed Roadway under Backfill Body Subjected to Blasting Load
Hongwei Deng, Fei Wu, Renze Ou
November 30, 2023 (v1)
Keywords: backfill body, blasting-induced damage, dynamic response, mine pillar recovery, preformed roadway
Tungsten, essential in the industrial, military, and civilian domains and deemed a strategic resource by various nations, necessitates careful consideration in room and pillar mines due to the potential instability and safety hazards posed by untouched mine pillars, making tungsten recovery crucial for worker safety and economic gain. This research aims to provide guidance for recovering tungsten from mine pillars and making mining operations safer for workers in the Xianglushan mine. Numerical simulations are conducted to study the mechanical response of a preformed roadway in a backfill body subjected to static and dynamic loads with various explosive distances and positions. Blasting vibration velocity and blasting-induced damage in the backfill body are extracted to evaluate the mechanical response of the backfill body. The numerical results indicate that the steel frame and preformed roadway remain stable under the influence of both gravity and the impact from blasting, using a ch... [more]
A Simple Strategy for the Simultaneous Determination of Dopamine, Uric Acid, L-Tryptophan and Theophylline Based on a Carbon Nano-Onions Modified Electrode
Rui An, Wenzhu Kuang, Zijian Li, Tiancheng Mu, Hongxia Luo
November 30, 2023 (v1)
Subject: Materials
Keywords: carbon nano-onions, dopamine, electrochemical sensing, glassy carbon electrode, L-tryptophan, theophylline, uric acid
In this work, carbon nano-onions (CNOs) with particle sizes of 5−10 nm were prepared by the multi-potential step method. High-resolution transmission electron microscopy, infrared spectroscopy and Raman spectroscopy characterize the effective synthesis of CNOs. CNOs/GCEs were prepared by depositing the prepared CNOs onto glassy carbon electrodes (GCEs) by a drop-coating method. Examination of the electrocatalytic activity of the CNOs/GCE sensor by simultaneously detecting dopamine (DA), uric acid (UA), L-tryptophan (Trp) and theophylline (TP) using a differential pulse voltammetry technique. The results showed that the linear ranges of DA, UA, Trp and TP were DA 0.01−38.16 μM, UA 0.06−68.16 μM, Trp 1.00−108.25 μM, and TP 8.16−108.25 μM, and the detection limits (S/N = 3) were 0.0039 μM, 0.0087 μM, 0.18 μM and 0.35 μM, respectively. The CNOS/GCE sensor had good stability and could be used for the detection of actual samples.
Multi-Sized Granular Suspension Transport Modeling for the Control of Lost Circulation and Formation Damage in Fractured Oil and Gas Reservoirs
Jinhua Liu, Yayun Zhang, Dujie Zhang, Fan Li, Hexiang Zhou, Chengyuan Xu, Weiji Wang
November 30, 2023 (v1)
Keywords: fractured reservoir, gas and geothermal resources, multi-sized granule retention, oil, permeability damage, production enhancement, suspended granule transport
Transport and retention of multi-sized suspended granules are common phenomena in fracture media of oil, gas and geothermal reservoirs. It can lead to severe permeability damage and productivity decline, which has a significant impact on the efficient development of underground resources. However, the granule transport and retention behaviors remain not well understood and quantified. The novel stochastic model is proposed for the multi-sized suspended granule transport in naturally fractured reservoirs accounting for granule retention and fracture clogging kinetics. A percolation fracture network is proposed considering fracture connectivity evolution during suspended granule transport. Granule retention and fracture clogging dynamics equations are proposed to account for incomplete fracture clogging by retained granules. The microscale stochastic model is allowed for upscaling to predict the multi-sized granule transport behavior in naturally fractured reservoirs. The model solution... [more]
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